ASO Flashcards
In acute streptococcal infection, the toxic immunogenic exoenzyme _____ is produced in response to Streptolysin O antigens.
Anti Streptolysin O (ASO)
pH of ASO latex
8.2
Composition of the ASO Latex Kit
- ASO latex
- Positive control
- Negative control
- Reusable test cards
- Pipettes/stirrers
The positive control consists of:
- Human serum with ASO >200 IU/mL
- Preservative
The negative serum consists of:
- Animal serum
- Preservative
Sample/specimen used in ASO Latex Agglutination Test
Serum
Composition of the ASO Latex reagent?
- Suspension of white latex particles coated with Streptolysin O (pH 8.2)
- Preservative
Considering that the reagent contains <0.1% sodium azide, what precautions should be observed?
- It may be toxic if ingested
- It may react with lead and copper plumbing to form explosive metal azides
Storage temperature of the latex and controls
2-8 °C
Storage position of latex and control vials
Vertical
Ideal storage conditions of the serum to be used for testing
Serum stable for 48 hours at 2-8 °C
Storage condition of the sera if longer storage conditions are necessary
Frozen at -20 °C
Samples should be free from these factors:
- Contamination
- Hemolysis
- Lipemia
Materials that are required but not supplied by the kit:
- Mechanical rotator (set at 100rpm)
- Vortex mixer
- 9 g/L saline solution
Which groups of hemolytic Streptococci liberate Streptolysin O antigens?
A, C, and G
Measurement of ____ is important in the investigation of post-streptococcal diseases.
ASO Antibody titre
At what temperature should the samples and reagents be during testing?
room temperature
Volume of sample to be used during testing
50 µL
Amount of control to be used during testing
1 drop
Amount of latex reagent to be used in testing
1 drop
In qualitative testing, the test should be read after ____
2 minutes
In qualitative testing, what could occur if the test is read longer than 2 minutes?
False positive
In qualitative testing, what equipment can be used in rotating the cards?
Mechanical rotator set at 100 rpm
In qualitative testing, what should be observed after rotating the cards?
Agglutination
In what ways can the ASO-latex reagent be mixed before using?
- Manually
- Vortex mixer
In the semi-quantitative test procedure, this solution is added first
50 µl of 9 g/L saline
Volume of ASO in a neat dilution
200 IU/mL
Volume of ASO in a 1:2 dilution
400 IU/mL
Volume of ASO in a 1:4 dilution
800 IU/mL
Volume of ASO in a 1:8 dilution
1600 IU/mL
What does the presence of a visible agglutination indicate?
Content of Anti-streptolysin ≥200 IU/mL
What test is done to a positive sera?
Titred by making serial two-fold dilutions in 9g/L saline
